water optical illusion

An amazing water optical illusion, you can easily do it: When the arrow is moved to a particular distance behind the glass, it looks like it reversed itself.   Watch the video…

When light passes from one material to another, it can bend or refract. In the experiment that you just completed, light traveled from the air, through the glass, through the water, through the back of the glass, and then back through the air, before hitting the arrow. Anytime that light passes from one medium, or material, into another, it refracts.

Just because light bends when it travels through different materials, doesn’t explain why the arrow reverses itself.